Can Sunday's election end Spain's endless deadlock?

However, the long political deadlock in Madrid has also affected Sanchez's influence in Brussels.

After attempts to form a coalition government of left-wing parties failed repeatedly earlier this year, it is still unclear if Spain will have - for the first time in its recent history - a coalition government, or if the socialist government of Sánchez will now get the support to rule with a minority government.

Only one thing obvious: Spanish politicians must somehow find a formula to form a stable government, which is able to unblock fundamental policies on standby for a long time - such as the new budgetary plans.

To do so, Sanchez has rejected the idea of a grand coalition with the conservatives of the Spanish Popular Party (PP) but has asked PP and centre-right party Ciudadanos (Citizens) to consider the possibility of a "technical abstention" in his investiture session.

This move could allow him to rule with a minority government.

End of bipartisanship?

Sanchez's centre-left Socialist Party (PSOE), which is likely emerge from Sunday's elections as the single largest party, according to the most recent polls, won the highest tally of seats in April but fell short of an absolute majority.

He tried to agree on a coalition programme with the leader of Unidas Podemos, Pablo Iglesias, but negotiations broke down, leading to a serious increase of distrust between the two parties.

Earlier this year, the spokeswoman of Unidas Podemos said that "there are only two options [for the upcoming government]: a coalition of right-wing or left-wing parties. It seems that the only one who does not understand this is Pedro Sánchez".

"Bipartisanship will no longer work in this country," she added.

When the different parties failed to form a government, a Spanish left-wing politician, Iñigo Errejon (a former co-founder of Unidas Podemos) announced the creation of a new party called Más País (More Country) that will run in Sunday's poll.

Errejon's new party adds even more uncertainty to Sunday's ballot, as the left vote is now more likely to be fragmented - helping the main conservative party to reach a majority, or prevent any bloc from doing so.

Catalonia's role

The Catalan issue is once again the main topic of political debate for this election - which has helped the far-right Vox party surge as the third option for Spaniards, according to the final polls.

Vox first entered regional government in December 2018 with 12 seats in the parliament of Andalusia, and at the general elections of April won 24 seats in the congress.

However, the last polls suggest that it could double this figure on Sunday.

If so, this could open the door for the conservative PP, which already secured the support of Vox in several regions and municipalities to form coalition governments with Citizens.

Meanwhile, thousands of law enforcement officers are set to be deployed in the region of Catalonia on Sunday's election day.

According to El País, sources close to the operation reveal that 2,500 officers of the National Police and 2,000 members of the Civil Guard will patrol the streets, together with another 8,000 members of the regional police force, the Mossos d'Esquadra.

This decision follows the recent street disturbances between radical independence activists and police, that left around 600 people injured, 200 protesters arrested, and 28 placed in custody.

The authorities of Barcelona have estimated the damages at over €2.5m.